Distribution of the marine and transitional terraces (Holocene) and geomorphological map of the Punta Catalina, Tierra del Fuego, Straits of Magellan, Chile (1:50,000 scale map – Map n° 4/12 - Second Edition)

Previous studies, carried out by the “Dipartimento di Scienze Geologiche, Ambientali e Marine” of “Università di Trieste” within the “Programma Nazionale di Ricerche in Antartide” (P.N.R.A.) and by the “Dipartimento di Scienze della Terra” of “Università di Cagliari” within the project “PVS – Regione Autonoma della Sardegna – Cile”, on the Straits of Magellan were mainly direct ed at sedimentological research on the sea bottoms and coastal belt of the eastern section (Atlantic opening). Similar wide ranging research was carried out also on the coastal belt of the western section (Pacific opening) from sea vessels, since it was inaccessible by land which is typically sheer (fiords). The first coastal studies were connected with sedimentological studies of the bottom, but were limited to research on the source of transport of the sediments as well as a regional definition of morphostructural units. Subsequent research along the coastal belt was carried out in greater detail with mapping of morphological units. During this second phase, greater attention was given to the study of palaeo-shorelines and different terrace orders of presumed marine and transitional origin (Brambati et alii, 1993a; 1993b). On the basis of initial geological, sedimentological and geomorphological results obtained, we made a zoning of the coastal belts along the Atlantic opening of the Straits which enabled us to print three sheets on a scale of 1:200,000 (De Muro et alii 1995, Brambati et alii 1995a e 1995b, Di Grande et alii 1995). Detailed studies and maps (scale 1:50,000) of the terraced sequences linked to Holo-Pleistocene glacio-eustatic variations are in course. The aim is to publish an Atlas accompanied by 12 geomorphological maps (of which this is the fourth) topographically based on 28 Chilean I.G.M. 1:50,000 scale maps of the area between Punta Dungeness and Bahía Inutíl (Di Grande et alii 1996a, 1996b and 1996c; De Muro et alii 1996 e 1997). The eastern entrance of the Straits of Magellan is characterized by the presence of two truncate cuspate forelands, typical high energy accretionary morphologies, formed during Holocene regressive phase. The northern foreland is called Punta Dungeness, in honour of the best known similar form in UK, and could be originated about 4.2 ka BP (Uribe and Zamora, 1981). The southern foreland, called Punta Catalina, lies in the north-easternmost part of Tierra del Fuego. Ir shows a strong analogy with Punta Dungeness foreland, and could be formed and developed as the opposite morphology (Fontolan and Simeoni, 1999). On the basis of air-photo interpretation, togher with field survey, almost nine different accretionary phases of Punta Catalina foreland can be recognized.